Field of the Invention
The present invention relates to an image forming apparatus. More particularly, the present invention relates to an image forming apparatus suited for use as a copying machine, a printer (such as LED printer and laser beam printer), a facsimile machine, a word processor, and the like that are configured to form images on recording media by using an electrophotographic image forming process.
Description of the Related Art
Hitherto, in an image forming apparatus using an electrophotographic image forming process, there has been known a process cartridge system in which photosensitive drums and developing units each housing a developing roller to act on the corresponding photosensitive drums and each containing developer (toner) to be used for image formation are integrated with each other. Further, there has also been known a developing cartridge system in which the cartridge has only the developing units independently of the drums. Those cartridge systems allow users themselves to perform maintenance of the apparatus without service engineers. Thus, those cartridge systems have been widely used in image forming apparatus.
Further, there has also been known a technology of arranging a moving member to which process cartridges and developing cartridges are mounted, and pulling out the moving member from an inside position of a main body of the image forming apparatus to an outside position so that an operation of replacing various types of cartridges can be performed. This technology allows users to easily replace cartridges containing the developer.
Further, there has been known an image forming apparatus having exposure openings formed in a moving member. Specifically, the exposure openings are formed so that laser beams emitted from an exposure device configured to form electrostatic latent images, which is arranged in a main body, are radiated on photosensitive drums as image bearing members (Japanese Patent Application Laid-Open No. 2010-181766).
In the above-mentioned related-art apparatus, however, there is a risk in that the toner (developer) adhering to the photosensitive drum or the developing roller is scattered inside and outside the apparatus through the exposure openings of the exposure device due to a shock caused by mounting and removing the moving member to and from the main body when various types of cartridges are replaced.
Therefore, the developer is required to be prevented from being scattered inside the main body when the moving member is moved.